Carotenoids are yellow to red pigments naturally present in plants, animals, seaweed, microorganisms, and the like and antioxidant action is known as the typical action thereof. In particular, xanthophylls containing an oxygen atom in the molecular structure, such as astaxanthin, fucoxanthin, lutein, canthaxanthin, and zeaxanthin, have high antioxidant action. In particular, fucoxanthin has been reported to have functionalities, such as antiobesity action, anticancer action, antidiabetic action, and antiinflammatory action, and has potential of exhibiting a high utility value as a functional material.
In general, even in the case of cells that produce carotenoid, the content of the carotenoid contained in the cells is low. For example, fucoxanthin contained in seaweed is extremely as small as about 0.01%. In order to take fucoxanthin in an amount which allows the fucoxanthin to exert effective functionalities, it is necessary to eat a huge amount of seaweed, which is not realistic. Therefore, in order to prepare fucoxanthin into a practical functional material, it is necessary to extract and purify fucoxanthin from seaweed with a large amount of solvent, and then highly purifying the same to about several % concentration by concentration.
As a method for highly purifying fucoxanthin, the following method is known. JP-A No. 2004-75634 (Patent Document 1) describes a method for removing impurities by treating an extract obtained from seaweed with activated carbon. However, according to the method, only partial impurities such as chlorophyll, adsorbing to the activated carbon, can be removed, so that the purification degree of the fucoxanthin is low. Furthermore, the fucoxanthin itself tends to be adsorbed to the activated carbon to be removed, and thus fucoxanthin cannot be prepared into a practical functional material only by this operation. JP-A No. 2009-120494 (Patent Document 2) describes a method including bringing an extract from brown algae into contact with a synthetic adsorption resin, and then eluting fucoxanthin adsorbing to the resin. However, according to the method, fucoxanthin can be highly purified up to about several % but a large amount of an expensive synthetic adsorption resin is used for obtainable fucoxanthin, which increases the cost, resulting in the fact that the method is economically disadvantageous. Moreover, in order to elute the fucoxanthin adsorbed to the surface of the synthetic adsorption resin, a large amount of solvent is required and also an operation of concentrating and distilling off the used solvent is required. However, since the fucoxanthin is very unstable to heat, an operation of concentrating and distilling off a large amount of solvent is required. Therefore, it can be said that the method for highly purifying fucoxanthin using the synthetic adsorption resin has poor production efficiency and also is industrially disadvantageous.
The production method including highly purifying fucoxanthin is disclosed as described above, but a method for highly purifying fucoxanthin without using the operation of concentrating a large amount of solvent has not been disclosed yet, so that problems with cost and operability in producing fucoxanthin have not been solved yet.